Gas generator and device for electrically contacting a gas generator

ABSTRACT

The invention relates to a gas generator for filling an airbag of a vehicle. Said gas generator ( 1 ) can be integrated into the vehicle in such a way that it is electrically insulated from the same, and can be directly connected to the electrical earth of the vehicle, especially to a defined earth potential, by means of a separate earth connection ( 30, 31 ). The invention thus provides an improved earth connection of the gas generator.

The invention relates to a gas generator for filling an airbag for amotor vehicle in accordance with the preamble of claim 1 and to a devicefor making electrical contact with a gas generator in accordance withthe preamble of claim 14.

Gas generators in motor vehicles serve the purpose of inflating airbags,as required, i.e. in particular in the case of an accident. The gasgenerator is in this case generally activated by means of an electricalsignal and is grounded to the ground potential of the vehicle. Withknown gas generators, used for grounding purposes are the fixing means,by means of which the gas generator or its housing is fixed to thevehicle. These electrically conductive fixing parts are used to connectthe gas generator to a likewise electrically conductive vehicle part, inparticular a body part or a metallic part of a motor vehicle seat. Thisconnection provides the contact between the gas generator housing andthe ground potential of the vehicle. The reliability of the grounding orconnection to the ground potential produced in this manner is dependenton a large number of external factors, such as the occurrence of leakagecurrents or the correct mounting of the respective fixing part, forexample. It is also possible for there to be multiple groundings whichmake defined grounding of the gas generator to a unique ground potentialimpossible. Furthermore, two or more gas generators which are arrangedat different points in the vehicle are connected to different groundpotentials of the vehicle, since the ground potential may assumedifferent values at different points of the motor vehicle, for example,owing to the occurrence of leakage currents.

DE 43 17 737 A1 describes a gas generator for filling an airbag. The gasgenerator is installed in the vehicle such that it is electricallyconnected to a hooter switch. The gas generator is connected to thenegative pole of the battery via a socket and a steering shaft, to whichthe hooter switch is also connected.

It is therefore the object of the invention to specify an improvedground connection for gas generators.

The object is achieved by a gas generator having the features of claim1. Accordingly, the gas generator can be installed such that it iselectrically insulated with respect to the vehicle and can be connecteddirectly to the electrical ground of the vehicle, in particular to adefined connection. The electrical insulation of the gas generator withrespect to the vehicle and the connection to a defined ground potentialmeans that the gas generator is at a defined ground potential. Even whena large number of gas generators are used which are installed atdifferent points in the vehicle, a ground potential which is identicalfor all of the gas generators can be prescribed, since the groundpotential does not depend on the installation location.

A direct connection of the ground connection of the gas generator is inthis case understood to mean that the ground connection is connected toa prescribed ground potential directly. This may be achieved, forexample, by means of an electrical line between the gas generator andthe point of the vehicle defining the ground potential, in particularone pole of the vehicle battery. The ground connection is thus inparticular not produced using vehicle seats, body parts or mechanicalfixing means.

Connecting the gas generator housing by means of the separate groundconnection to the electrical ground of the vehicle is advantageous sincethe known gas generators have been connected to ground via the gasgenerator housing of the gas generator. These gas generators can thusstill be used.

Simple installation is achieved by it being possible for the groundconnection to be clamped in between the gas generator housing and anignition plug such that the ground connection is in contact with the gasgenerator housing. When connecting the ignition plug to the gasgenerator, at the same time a defined ground connection of the gasgenerator housing can thus be produced by clamping the groundconnection. This can be achieved in a single working step by insertingthe ignition plug. Furthermore, owing to the clamping of the groundconnection between the ignition plug and the gas generator housing, nofurther connection for the ground connection is required, with theresult that the usual design principle of known gas generators can bemaintained. Reliable connection of the ground connection to the gasgenerator is achieved by it being possible for the ignition plug to belatched onto the gas generator and/or the gas generator housing. Thisprevents the ignition plug or the ground connection clamped between theignition plug and the gas generator housing from being released owing tomechanical vibrations. However, simple installation is made possible bythe latching of the plug connection.

In order to make contact in a simple manner with the gas generatorhousing when the ground connection is clamped between the gas generatorhousing and an ignition plug, the ground connection has an annularcontact region which serves the purpose of making contact with the gasgenerator housing. The annular contact region may comprise, for example,a contact region of the ignition plug, but may at the same time havesmaller dimensions than the remainder of the housing of the ignitionplug. By this means both the contact region of the ignition plug and theground connection can be brought into contact with the gas generator atthe same time. It is possible for reliable contact to be made with thegas generator housing in the annular contact region by the annularcontact region being resilient or in the form of a spring disk. Evenmanufacturing tolerances or an ignition plug which is inserted such thatit does not exactly fit or which is not completely inserted can becompensated for by the resilient, annular contact region, in which casethe resilient, annular contact region also stresses the ignition plugwith respect to the gas generator housing and thus prevents rattling,for example.

Simple electrical insulation of the gas generator with respect to thevehicle can be achieved by the gas generator housing being electricallyinsulating on its outer side and, in particular, having a coating forthe purpose of electrically insulating it with respect to the vehicle.When such an electrical insulation is used on the outer side of the gasgenerator housing, the otherwise conventional, electrically conductivefixing parts can still be used for the purpose of fixing the gasgenerator to the vehicle. However, the gas generator is thenelectrically insulated with respect to the vehicle.

In order to insulate the gas generator with respect to the vehicle, anelectrically insulating fixing device may also be used which is, inparticular, at least partially made of an electrically insulatingmaterial or has an insulating region.

It is also possible to connect the gas generator directly to theelectrical ground of the vehicle by means of a plug connection. A plugconnection has the conventional advantages that it is a secureconnection and that it is easy to handle. In one advantageousembodiment, the ground connection is integrated in an ignition plug.

The object is further achieved by a device for making electrical contactwith a gas generator having the features of claim 14.

Accordingly, the device has an ignition plug for making electricalcontact with an ignition device of a gas generator, a separate groundconnection being provided for the purpose of directly connecting the gasgenerator to the electrical ground of the vehicle, in particular to adefined ground potential. The device thus at the same time serves thepurpose of making contact with the ignition device of the gas generatorby means of the ignition plug, and also serves the purpose of producinga direct connection between the gas generator and the ground potentialof the vehicle.

The ground connection is advantageously produced between the gasgenerator housing of the gas generator and the electrical ground of thevehicle. In this case, in turn, as is described above, the groundconnection can be clamped in between the ignition plug and a gasgenerator housing such that the ground connection is in contact with thegas generator housing. For simple installation and cost-effectiveproduction, it is possible for the ground connection to have an annularcontact region which may also be, in particular, resilient or in theform of a spring disk. It is thus possible to produce a reliableconnection between the ground connection and the gas generator housing.

The invention has the advantage that a gas generator or the gasgenerator housing is connected in a reliable manner to the groundpotential of the vehicle. In this case, in each case only one single,defined grounding path is provided, with the result that the risk ofmultiple groundings and thus the risk of potentials which are notuniquely defined are eliminated. This provides a functionally reliableunit.

The invention will be explained by way of example in the text whichfollows with reference to the drawings of the figures, in which:

FIG. 1 shows a perspective view of a gas generator according to theinvention having an ignition plug and a ground connection having anannular contact element; and

FIG. 2 shows a perspective view of the gas generator according to theinvention shown in FIG. 1, the ignition plug and the ground connectionbeing separate from the gas generator.

FIG. 1 shows a gas generator 1 having a gas generator housing 10. Thisgas generator 1 can be connected, via fixing means (not shown here), tovehicle parts (likewise not shown) of the vehicle. The insulation of thegas generator 1 from the vehicle is achieved by means of an insulatingcoating of the gas generator housing 10.

Electrical contact is made with the ignition device (not shown here),which is located in the interior of the gas generator 1 and by means ofwhich the gas generator 1 is activated, via an ignition plug 20. FIG. 1shows the ignition plug 20 in a position in which it is connected to thegas generator 1, the ignition device being in electrical contact withthe respective ignition lines 23. A latching mechanism 22 serves thepurpose of fixedly latching the ignition plug 20 onto the gas generator1.

Arranged between the housing of the ignition plug 20 and the gasgenerator housing 10 is an annular contact region 31 of the groundconnection 30. As is shown in FIG. 2, the ignition plug 20 and theannular contact region 31 of the ground connection 30 are separatecomponents. The annular contact region 31 of the ground connection 30 isclamped in between the housing of the ignition plug 20 and the gasgenerator housing 10 by connecting the ignition plug 20 to the gasgenerator 1. The gas generator housing 10 does not have an insulatinglayer in this contact region, with the result that the annular contactregion 31 is in direct contact with the gas generator housing 10. Thehousing of the ignition plug 20, on the other hand, is made of aninsulating material, with the result that a ground contact is producedbetween the ground connection 30. and the gas generator housing 10 bythe annular contact element 31 being clamped in.

Reliable contact is made between the annular contact region 31 and thegas generator housing 10 by the annular contact region 31 beingresilient. The annular contact region 31 is thus latched, with theresilient, annular contact region 31 being subjected to springprestress, by the ignition plug 20 being pressed on and the latchingdevice 22 of the ignition plug 20 subsequently being latched. Thisensures that the annular contact region 31 is also in reliable contactwith the gas generator housing 10 even if the ignition plug is subjectedto relatively high tolerances.

The ground connection 30 is connected on a central potential rail (notshown here) which defines the ground potential of the vehicle. The gasgenerator 1 is therefore connected to the ground potential of thevehicle directly and exclusively by means of the ground connection 30.

FIG. 2 shows the contact region 21 of the ignition plug 20 which isconnected to a corresponding contact region (not shown) of the gasgenerator 1.

FIG. 2 shows the ignition plug 20 once again when it is separated fromthe gas generator housing 10. The ground connection 30 has an annularcontact region 31 which is resilient. The ignition plug 20 is passedthrough the annular contact region 31 of the ground connection 30 forthe purpose of connecting it to the gas generator housing 10. In thiscase, the diameter of the annular contact region 31 is selected suchthat parts of the housing of the ignition plug 20 protrude beyond theannular contact region 31. Housing parts of the ignition plug 20 thusfixedly clamp the annular contact region 31 between the housing parts ofthe ignition plug 20 and the gas generator housing 10 when the ignitionplug 20 is connected to the gas generator housing 10 or to a plugreceptacle arranged thereon. By this means, the annular contact region31 of the ground connection 30 is clamped directly onto the gasgenerator housing 10 and direct contact is made between the two.

1-17. (canceled)
 18. A gas generator for filling an airbag in a vehiclecomprising: a gas generator housing; an ignition plug operativelyconnected to the gas generator housing; and a separate groundconnection, clamped in between the ignition plug such that the separateground connection comes into electrical contact with the gas generatorhousing.
 19. The gas generator as claimed in claim 18, wherein the gasgenerator housing is connected to the electrical ground of the vehicleby the separate ground connection.
 20. The gas generator as claimed inclaim 19, further comprising: a latching mechanism, wherein the ignitionplug is latched onto both the gas generator and the gas generatorhousing or either the gas generator or the gas generator housing by thelatching mechanism.
 21. The gas generator as claimed in claim 19,wherein the ground connection has an annular contact region, it beingpossible for contact to be made between the annular contact region andthe gas generator housing.
 22. The gas generator as claimed in claim 21,wherein the annular contact region is resilient.
 23. The gas generatoras claimed in claim 22, wherein the annular contact region is a springdisk.
 24. The gas generator as claimed in claim 18, wherein the gasgenerator housing is electrically insulated on its outer side.
 25. Thegas generator as claimed in claim 24, wherein the gas generator housinghas a coating for electrically insulating it with respect to thevehicle.
 26. The gas generator as claimed in claim 18, furthercomprising: a fixing device, fixing the gas generator to the vehicle,wherein the fixing device electrically insulates the gas generator withrespect to the vehicle.
 27. The gas generator as claimed in claim 26,wherein the fixing device is an electrical insulator.
 28. The gasgenerator as claimed in claim 18, wherein the gas generator and/or thegas generator housing can be connected to the electrical ground of thevehicle by a plug connection.
 29. The gas generator as claimed in claim28, wherein the plug connection makes electrical contact with anignition device of the gas generator.
 30. A device for making electricalcontact with a gas generator, comprising: an ignition plug, and aseparate ground connection, clamped in between the ignition plug and thegas generator such that the separate ground connection is in contactwith the gas generator.
 31. The device as claimed in claim 30, whereinthe separate ground connection connects a gas generator housing to theelectrical ground of a vehicle.
 32. The device as claimed in claim 30,wherein the ground connection has an annular contact region, it beingpossible for contact to be made between said contact region and the gasgenerator housing.
 33. The device as claimed in claim 32, wherein theannular contact region is resilient.
 34. The device as claimed in claim32, wherein the annular contact region is a spring disk.